perf(router): reuse ATC context in router match instead of creating a…

… new context (#12258)

To avoid frequent memory allocation/deallocations.

KAG-3448

.requirements

@@ -10,7 +10,7 @@ LUA_KONG_NGINX_MODULE=4fbc3ddc7dcbc706ed286b95344f3cb6da17e637 # 0.8.0
 LUA_RESTY_LMDB=951926f20b674a0622236a0e331b359df1c02d9b # 1.3.0
 LUA_RESTY_EVENTS=8448a92cec36ac04ea522e78f6496ba03c9b1fd8 # 0.2.0
 LUA_RESTY_WEBSOCKET=60eafc3d7153bceb16e6327074e0afc3d94b1316 # 0.4.0
-ATC_ROUTER=b0d5e7e2a2ca59bb051959385d3e42d96c93bb98 # 1.2.0
+ATC_ROUTER=ac71b24ea5556b38b0f9903850ed666c36ad7843 # 1.4.1
 
 KONG_MANAGER=v3.4.1.0
 NGX_WASM_MODULE=21732b18fc46f409962ae77ddf01c713b568d078 # prerelease-0.1.1

changelog/unreleased/kong/atc_reuse_context.yml

@@ -0,0 +1,3 @@
+message: "Reuse match copntext between requests to avoid frequent memory allocation/deallocation"
+type: performance
+scope: Core

changelog/unreleased/kong/bump-atc-router.yml

@@ -0,0 +1,3 @@
+message: Bumped atc-router from 1.2.0 to 1.4.1
+type: dependency
+scope: Core

kong/router/atc.lua

@@ -4,6 +4,7 @@ local _MT = { __index = _M, }
 
 local buffer = require("string.buffer")
 local schema = require("resty.router.schema")
+local context = require("resty.router.context")
 local router = require("resty.router.router")
 local lrucache = require("resty.lrucache")
 local tb_new = require("table.new")
@@ -35,7 +36,7 @@ local check_select_params  = utils.check_select_params
 local get_service_info     = utils.get_service_info
 local route_match_stat     = utils.route_match_stat
 local get_cache_key        = fields.get_cache_key
-local get_atc_context      = fields.get_atc_context
+local fill_atc_context      = fields.fill_atc_context
 
 
 local DEFAULT_MATCH_LRUCACHE_SIZE = utils.DEFAULT_MATCH_LRUCACHE_SIZE
@@ -225,7 +226,7 @@ local function new_from_scratch(routes, get_exp_and_priority)
   local fields = inst:get_fields()
 
   return setmetatable({
-      schema = CACHED_SCHEMA,
+      context = context.new(CACHED_SCHEMA),
       router = inst,
       routes = routes_t,
       services = services_t,
@@ -416,7 +417,9 @@ function _M:matching(params)
   params.host = host
   params.port = port
 
-  local c, err = get_atc_context(self.schema, self.fields, params)
+  self.context:reset()
+
+  local c, err = fill_atc_context(self.context, self.fields, params)
 
   if not c then
     return nil, err
@@ -556,7 +559,9 @@ function _M:matching(params)
                       params.dst_ip, params.dst_port,
                       sni)
 
-  local c, err = get_atc_context(self.schema, self.fields, params)
+  self.context:reset()
+
+  local c, err = fill_atc_context(self.context, self.fields, params)
   if not c then
     return nil, err
   end

kong/router/fields.lua

@@ -1,5 +1,4 @@
 local buffer = require("string.buffer")
-local context = require("resty.router.context")
 
 
 local type = type
@@ -288,8 +287,8 @@ local function get_cache_key(fields, params, ctx)
 end
 
 
-local function get_atc_context(schema, fields, params)
-  local c = context.new(schema)
+local function fill_atc_context(context, fields, params)
+  local c = context
 
   local res, err =
   fields_visitor(fields, params, nil, function(field, value)
@@ -354,7 +353,7 @@ end
 
 return {
   get_cache_key = get_cache_key,
-  get_atc_context = get_atc_context,
+  fill_atc_context = fill_atc_context,
 
   _set_ngx = _set_ngx,
 }